/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.jackrabbit.webdav.version;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import javax.servlet.http.HttpServletResponse;

import org.apache.jackrabbit.webdav.DavException;
import org.apache.jackrabbit.webdav.xml.DomUtil;
import org.apache.jackrabbit.webdav.xml.ElementIterator;
import org.apache.jackrabbit.webdav.xml.Namespace;
import org.apache.jackrabbit.webdav.xml.XmlSerializable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;

/**
 * <code>OptionsInfo</code> represents the Xml request body, that may be present
 * with a OPTIONS request. <br>
 * The DAV:options element is specified to have the following form.
 * 
 * <pre>
 * &lt;!ELEMENT options ANY&gt;
 * ANY value: A sequence of elements each at most onces.
 * </pre>
 * 
 * Note, that this is a simplified implementation of the very generic
 * definition: We assume that the DAV:options element only contains empty child
 * elements, such as e.g. {@link DeltaVConstants#XML_VH_COLLECTION_SET
 * DAV:version-history-collection-set} or
 * {@link DeltaVConstants#XML_WSP_COLLECTION_SET DAV:workspace-collection-set}.
 * 
 * @see DeltaVConstants#XML_VH_COLLECTION_SET
 * @see DeltaVConstants#XML_WSP_COLLECTION_SET
 * @see DeltaVConstants#XML_ACTIVITY_COLLECTION_SET
 */
public class OptionsInfo implements XmlSerializable {

	private static Logger log = LoggerFactory.getLogger(OptionsInfo.class);

	/**
	 * Build an <code>OptionsInfo</code> object from the root element present in
	 * the request body.
	 * 
	 * @param optionsElement
	 * @return
	 * @throws DavException
	 *             if the optionsElement is <code>null</code> or not a
	 *             DAV:options element.
	 */
	public static OptionsInfo createFromXml(Element optionsElement)
			throws DavException {
		if (!DomUtil.matches(optionsElement, DeltaVConstants.XML_OPTIONS,
				DeltaVConstants.NAMESPACE)) {
			log.warn("DAV:options element expected");
			throw new DavException(HttpServletResponse.SC_BAD_REQUEST);
		}
		OptionsInfo oInfo = new OptionsInfo();
		ElementIterator it = DomUtil.getChildren(optionsElement);
		while (it.hasNext()) {
			// todo: not correct since assuming its the deltaV-namespace
			oInfo.entriesLocalNames.add(it.nextElement().getLocalName());
		}
		return oInfo;
	}

	private final Set<String> entriesLocalNames = new HashSet<String>();

	/**
	 * Private constructor used to create an OptionsInfo from Xml.
	 */
	private OptionsInfo() {
	}

	/**
	 * Create a new OptionsInfo with the specified entries. Each entry will be
	 * converted to an empty Xml element when calling <code>toXml</code>. As
	 * namespace {@link DeltaVConstants#NAMESPACE} is used.
	 * 
	 * @param entriesLocalNames
	 */
	public OptionsInfo(String[] entriesLocalNames) {
		if (entriesLocalNames != null) {
			for (String entriesLocalName : entriesLocalNames) {
				this.entriesLocalNames.add(entriesLocalName);
			}
		}
	}

	/**
	 * Returns true if a child element with the given name and namespace is
	 * present.
	 * 
	 * @param localName
	 * @param namespace
	 * @return true if such a child element exists in the options element.
	 */
	public boolean containsElement(String localName, Namespace namespace) {
		if (DeltaVConstants.NAMESPACE.equals(namespace)) {
			return entriesLocalNames.contains(localName);
		}
		return false;
	}

	/**
	 * @see org.apache.jackrabbit.webdav.xml.XmlSerializable#toXml(Document)
	 * @param document
	 */
	public Element toXml(Document document) {
		Element optionsElem = DomUtil.createElement(document,
				DeltaVConstants.XML_OPTIONS, DeltaVConstants.NAMESPACE);
		Iterator<String> it = entriesLocalNames.iterator();
		while (it.hasNext()) {
			String localName = it.next();
			DomUtil.addChildElement(optionsElem, localName,
					DeltaVConstants.NAMESPACE);
		}
		return optionsElem;
	}
}